1. Field of the Invention
The present invention relates to a method of manufacturing a thin-film magnetic head having at least an induction-type electromagnetic transducer.
2. Description of the Related Art
Performance improvements in thin-film magnetic heads have been sought as a real recording density of hard disk drives has increased. Among the thin-film magnetic heads, widely used are composite thin-film magnetic heads made of a layered structure including a recording head having an induction-type electromagnetic transducer for writing and a reproducing head having a magnetoresistive element (that may be hereinafter called an MR element) for reading.
In general, a recording head incorporates: a medium facing surface (air bearing surface) that faces toward a recording medium; a bottom pole layer and a top pole layer that are magnetically coupled to each other and include magnetic pole portions opposed to each other and located in regions of the pole layers on a side of the medium facing surface; a recording gap layer provided between the magnetic pole portions of the top and bottom pole layers; and a thin-film coil at least part of which is disposed between the top and bottom pole layers and insulated from the top and bottom pole layers.
Higher track densities on a recording medium are essential to enhancing the recording density among the performances of a recording head. To achieve this, it is required to implement a recording head of a narrow track structure in which the track width, that is, the width of the two magnetic pole portions opposed to each other on a side of the medium facing surface, with the recording gap layer disposed in between, is reduced down to microns or the order of submicron. Semiconductor process techniques are utilized to achieve such a structure.
With decreasing track width, it becomes harder to generate a high-density magnetic flux between the two magnetic pole portions that are opposed to each other with the recording gap layer in between. On that account, it is desirable that the magnetic pole portions be made of a magnetic material having a higher saturation flux density.
As the frequency of recording signals is made higher to increase the recording density, a higher speed of change of magnetic flux, or equivalently, a reduction in flux rise time, is required of recording heads. Furthermore, less degradation in the recording characteristics of the recording heads such as overwrite property and non-linear transition shift are required at higher frequency bands. To meet those requirements, it is desirable to reduce a yoke length. Decreasing the winding pitch of the thin-film coil is effective for reducing the yoke length.
One of known techniques for decreasing the winding pitch of a thin-film coil is to form a recess in the bottom pole layer so as to place the thin-film coil in the recess, as disclosed in U.S. Pat. No. 6,043,959 and Published Unexamined Japanese Patent Application (KOKAI) No. 2001-76316, for example.
According to the method of manufacturing a thin-film magnetic head described in U.S. Pat. No. 6,043,959, the bottom pole layer, the top pole layer, and the thin-film coil are formed through the following steps. Initially, the bottom pole layer patterned into a predetermined shape is formed. The recording gap layer and a magnetic layer are then formed on the bottom pole layer in succession. Part of the magnetic layer is coupled to the bottom pole layer. Then, a mask is formed to cover portions of the magnetic layer where to form the magnetic pole portion of the top pole layer and where to form a coupling portion of the top pole layer to be coupled to the bottom pole layer. The magnetic layer, the recording gap layer and the bottom pole layer are etched by using this mask. The magnetic layer thus etched makes a pole portion layer that is to be the magnetic pole portion of the top pole layer, and a coupling layer that is to be the coupling portion mentioned above. The above-mentioned etching also forms a trim structure, in which sidewalls of the magnetic pole portion of the top pole layer, the recording gap layer and at least part of the bottom pole layer are formed vertically in a self-aligned manner. The etching also provides the bottom pole layer with a recess in which the thin-film coil is to be placed. An insulating film is then formed all over, and thereafter, the thin-film coil is formed by plating on the insulating film inside the recess. Then, a thick insulating layer is formed all over and the top surface of this insulating layer is flattened to expose the pole portion layer and the coupling layer of the top pole layer. On the flattened surface, a yoke portion layer of the top pole layer is formed so that the pole portion layer and the coupling layer are coupled to each other.
According to the method of manufacturing a thin-film magnetic head described in Published Unexamined Japanese Patent Application (KOKAI) No. 2001-76316, the bottom pole layer, the top pole layer, and the thin-film coil are formed through the following steps. Initially, a first part of the bottom pole layer patterned into a predetermined shape is formed. Next, a second part to be the magnetic pole portion of the bottom pole layer and a third part to be coupled to the top pole layer are formed on the first part. The first, second and third parts makes up the bottom pole layer having a recess in which the thin-film coil is to be placed. An insulating film is then formed all over, and thereafter, the thin-film coil is formed by plating on the insulating film inside the recess. Then, a thick insulating layer is formed all over, and the top surface of this insulating layer is flattened to expose the second and third parts. The recording gap layer is formed on the flattened surface. In the recording gap layer, a contact hole is formed at a portion thereof located on the third part. Then, the top pole layer is formed on the recording gap layer. The top pole layer is connected to the third part through the contact hole. Using the magnetic pole portion of the top pole layer as a mask, the bottom pole layer and the recording gap layer are etched to form a trim structure.
In the methods of forming a thin-film magnetic head described in U.S. Pat. No. 6,043,959 and Published Unexamined Japanese Patent Application (KOKAI) No. 2001-76316, the bottom pole layer is first patterned to have a recess therein, and thereafter the thin-film coil is formed in the recess. The thin-film coil is formed by frame plating through the following steps. Initially, a photoresist frame is formed by photolithography. Then, a thin electrode film is formed to cover this frame. With an electric current passed through this electrode film, the thin-film coil is formed by electroplating. In the case of forming the thin-film coil by frame plating, a fine frame is required to attain a smaller winging pitch of the thin-film coil.
To form the thin-film coil in the recess of the bottom pole layer as described above, the frame must be formed on the uneven bottom pole layer. However, it is difficult to form a fine frame on such an uneven base by photolithography. The reason for this is that rays of light used for exposure of photolithography are reflected off the electrode film lying on the sidewalls of the recess. The photoresist is exposed to the reflected rays as well, which makes it difficult to form a fine frame with precision. Consequently, for example, if a thin-film coil having a line width of winding of 0.3 xcexcm or less, or a winding pitch of 0.5 xcexcm or less, and a height of 1.5 xcexcm or more is to be formed in the recess of the bottom pole layer by the existing photolithography techniques, the yield of the thin-film coil becomes extremely low. Thus, it has been practically difficult to form such a coil.
It is an object of the invention to provide a method of manufacturing a thin-film magnetic head which makes it possible to form a fine thin-film coil with high precision and consequently, to manufacture a thin-film magnetic head having a small yoke length and excellent recording characteristics at high frequency bands.
A first method of the invention is provided for manufacturing a thin-film magnetic head comprising: a medium facing surface that faces toward a recording medium; a first pole layer and a second pole layer that are magnetically coupled to each other and include magnetic pole portions opposed to each other and located in regions of the pole layers on a side of the medium facing surface; a gap layer provided between the magnetic pole portions of the first and second pole layers; and a thin-film coil at least part of which is disposed between the first and second pole layers and insulated from the first and second pole layers.
The first method of manufacturing the thin-film magnetic head comprises the steps of:
forming a magnetic layer to be used for forming the first pole layer, the magnetic layer having a wholly flat top surface:
forming the thin-film coil on the magnetic layer;
completing the first pole layer by at least either patterning the magnetic layer or forming another magnetic layer on the magnetic layer, after the thin-film coil is formed;
forming the gap layer on the magnetic pole portion of the first pole layer; and
forming the second pole layer on the gap layer and the thin-film coil.
According to the first method of manufacturing the thin-film magnetic head of the invention, after forming the thin-film coil on the magnetic layer having a wholly flat surface, the first pole layer is completed by at least either patterning the magnetic layer or forming another magnetic layer on the magnetic layer. After that, in this manufacturing method, the gap layer and the second pole layer are formed.
A second method of the invention is provided for manufacturing a thin-film magnetic head comprising: a medium facing surface that faces toward a recording medium; a first pole layer and a second pole layer that are magnetically coupled to each other and include magnetic pole portions opposed to each other and located in regions of the pole layers on a side of the medium facing surface; a gap layer provided between the magnetic pole portions of the first and second pole layers; and a thin-film coil at least part of which is disposed between the first and second pole layers and insulated from the first and second pole layers, wherein: the first pole layer includes a first layer disposed to face toward the thin-film coil, and a second layer disposed closer to the medium facing surface than the thin-film coil and connected to a surface of the first layer that is closer to the gap layer.
The second method of manufacturing the thin-film magnetic head comprises the steps of:
forming a magnetic layer that is to be the first layer and has a wholly flat top surface;
forming the thin-film coil on the magnetic layer;
forming the second layer on the magnetic layer after the thin-film coil is formed;
forming the gap layer on the second layer; and
forming the second pole layer on the gap layer and the thin-film coil.
According to the second method of manufacturing the thin-film magnetic head of the invention, the thin-film coil is formed on the magnetic layer that is to be the first layer of the first pole layer and has a wholly flat surface. Then, the second layer of the first pole layer is formed on the magnetic layer. After that, in this manufacturing method, the gap layer and the second pole layer are formed.
The second method of manufacturing the thin-film magnetic head of the invention may further comprise the step of completing the first layer by patterning the magnetic layer after the second layer is formed. In this case, in the step of forming the thin-film coil, an insulating film may be formed on the magnetic layer in a region in which the thin-film coil is to be formed; then an electrode film for electroplating may be formed to cover the magnetic layer and the insulating film; and then electroplating may be performed using the electrode film to thereby form the thin-film coil. Furthermore, in the step of forming the second layer, a portion of the electrode film other than a portion thereof underlying the thin-film coil may be removed before forming the second layer on the magnetic layer.
In the second method of manufacturing the thin-film magnetic head of the invention, the second pole layer may be a flat layer.
A third method of the invention is provided for manufacturing a thin-film magnetic head comprising: a medium facing surface that faces toward a recording medium; a first pole layer and a second pole layer that are magnetically coupled to each other and include magnetic pole portions opposed to each other and located in regions of the pole layers on a side of the medium facing surface; a gap layer provided between the magnetic pole portions of the first and second pole layers; and first and second thin-film coils at least part of each of which is disposed between the first and second pole layers and insulated from the first and second pole layers, wherein the first pole layer includes a first layer disposed to face toward the first and second thin-film coils, and a second layer disposed closer to the medium facing surface than the first and second thin-film coils and connected to a surface of the first layer that is closer to the gap layer.
The third method of manufacturing the thin-film magnetic head of the invention comprises the steps of:
forming a magnetic layer that is to be the first layer and has a wholly flat top surface;
forming the first thin-film coil on the magnetic layer;
forming the second layer on the magnetic layer after the first thin-film coil is formed;
completing the first layer by patterning the magnetic layer after the second layer is formed;
forming the second thin-film coil so that at least part of the second thin-film coil is disposed in a space between turns of the first thin-film coil;
forming the gap layer on the second layer; and
forming the second pole layer on the gap layer, the first thin-film coil and the second thin-film coil.
According to the third method of manufacturing the thin-film magnetic head of the invention, the first thin-film coil is formed on the magnetic layer that is to be the first layer of the first pole layer and has a wholly flat top surface, and then, the second layer is formed on the magnetic layer. After that, the magnetic layer is patterned to complete the first layer. Then, in this manufacturing method, the second thin-film coil is formed so that at least part thereof is disposed in a space between turns of the first thin-film coil, followed by formation of the gap layer and the second pole layer.
In the third method of manufacturing the thin-film magnetic head of the invention, in the step of forming the first thin-film coil, an insulating film for the first thin-film coil may formed on the magnetic layer in a region in which the first thin-film coil is to be formed; then, an electrode film for the first thin-film coil may be formed to cover the magnetic layer and the insulating film for the first thin-film coil; and then electroplating may be performed using the electrode film for the first thin-film coil to thereby form the first thin-film coil. Furthermore, in the step of forming the second layer, a portion of the electrode film for the first thin-film coil other than a portion thereof underlying the first thin-film coil may be removed before forming the second layer on the magnetic layer.
In the third method of manufacturing the thin-film magnetic head of the invention, in the step of completing the first layer, a mask layer may be formed to cover the first thin-film coil and the second layer, and then a portion of the magnetic layer that is not covered with the mask layer may be removed by etching, to thereby complete the first layer.
In the third method of manufacturing the thin-film magnetic head of the invention, the step of forming the second thin-film coil may include the steps of:
forming an inter-coil insulating film to cover the first thin-film coil;
forming a first insulating layer to fill the space between the turns of the first thin-film coil;
forming a second insulating layer to cover the inter-coil insulating film and the first insulating layer;
polishing the second insulating layer so that the first insulating layer is exposed and top surfaces of the first and second insulating layers are flattened;
removing the first insulating layer from the space between the turns of the first thin-film coil; and
forming the second thin-film coil so that at least part of the second thin-film coil is disposed in the space between the turns of the first thin-film.
In the third method of manufacturing the thin-film magnetic head of the invention, the step of forming the second thin-film coil may include the steps of:
forming a first insulating layer to fill the space between the turns of the first thin-film coil;
forming a second insulating layer to cover the first insulating layer;
polishing the second insulating layer so that the first insulating layer is exposed and top surfaces of the first and second insulating layers are flattened;
removing the first insulating layer from the space between the turns of the first thin-film coil;
forming an inter-coil insulating film to cover the first thin-film coil; and
forming the second thin-film coil so that at least part of the second thin-film coil is disposed in the space between the turns of the first thin-film coil.
In the third method of manufacturing the thin-film magnetic head of the invention, the step of forming the second thin-film coil may include the steps of:
forming an inter-coil insulating film to cover the first thin-film coil;
forming an electrode film for the second thin-film coil to cover the inter-coil insulating film; and
forming the second thin-film coil by electroplating using the electrode film for the second thin-film coil so that at least part of the second thin-film coil is disposed in the space between the turns of the first thin-film coil.
In the third method of manufacturing the thin-film magnetic head of the invention, the first pole layer may further include a third layer, one of surfaces of the third layer being connected to a surface of the second layer closer to the gap layer, and the other one of the surfaces of the third layer being adjacent to the gap layer, and the method may further comprise the step of forming the third layer after the second thin-film coil is formed. In this case, in the step of forming the third layer, top surfaces of the first and second thin-film coils may be flattened; then, a coil coat insulating film may be formed to cover the top surfaces of the first and second thin-film coils; then, the third layer may be formed on the second layer; and then top surfaces of the third layer and the coil coat insulating film may be flattened.
In the third method of manufacturing the thin-film magnetic head of the invention, the second pole layer may be a flat layer.
Other and further objects, features and advantages of the invention will appear more fully from the following description.